Super Tuesday was on March 3 2020. Amy Klobuchar dropped out on March 2 2020 and endorsed Biden. Pete Buttigieg dropped out March 1 2020 and endorsed Biden.

The associated press wouldn't even call a winner for the Iowa caucus due to how poorly it was run https://apnews.com/article/fc6777e93b8c50b2fd20e0d31fcc43b3

There were definitely some interesting things going on in the 2020 Democratic primaries.